Add very basic compressed texture support

Allow direct loading of pkm texture files into Image. This can
be extended to additional texture types, and then eventually
turned into a full plugin architexture.

[ChangeLog][Qt Quick] Allow direct loading of pkm texture files
into Image. For example: Image { source: "myImage.pkm" }

Change-Id: I1baed6c3e85a15752da8adc675482d874c9355ab
Task-number: QTBUG-59872
Task-number: QTBUG-29451
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>

9 files changed, 523 insertions, 7 deletions

diff --git a/examples/quick/textureprovider/main.cpp b/examples/quick/textureprovider/main.cpp
index ea4f73127d..f92d34ada5 100644
--- a/examples/quick/textureprovider/main.cpp
+++ b/examples/quick/textureprovider/main.cpp
@@ -48,6 +48,10 @@ int main(int argc, char* argv[])
     QGuiApplication app(argc,argv);
     QQuickView view;
 
+    /*
+          NOTE: ETC compressed textures in PKM files are supported out-of-the-box since Qt 5.10.
+          However, we retain this example to show how custom texture providers can be integrated.
+    */
     EtcProvider *provider = new EtcProvider();
     provider->setBaseUrl(QUrl("qrc:///textureprovider/"));
     view.engine()->addImageProvider("etc", provider);
diff --git a/src/quick/scenegraph/compressedtexture/qsgpkmhandler.cpp b/src/quick/scenegraph/compressedtexture/qsgpkmhandler.cpp
new file mode 100644
index 0000000000..1b8882e9a5
--- /dev/null
+++ b/src/quick/scenegraph/compressedtexture/qsgpkmhandler.cpp
@@ -0,0 +1,209 @@
+/****************************************************************************
+**
+** Copyright (C) 2017 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtQuick module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qsgpkmhandler_p.h"
+
+#include <QFile>
+#include <QDebug>
+#include <qendian.h>
+#include <qopenglfunctions.h>
+#include <qqmlfile.h>
+
+//#define ETC_DEBUG
+
+#ifndef GL_ETC1_RGB8_OES
+    #define GL_ETC1_RGB8_OES 0x8d64
+#endif
+
+#ifndef GL_COMPRESSED_RGB8_ETC2
+    #define GL_COMPRESSED_RGB8_ETC2 0x9274
+#endif
+
+#ifndef GL_COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2
+    #define GL_COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2 0x9276
+#endif
+
+#ifndef GL_COMPRESSED_RGBA8_ETC2_EAC
+    #define GL_COMPRESSED_RGBA8_ETC2_EAC 0x9278
+#endif
+
+QT_BEGIN_NAMESPACE
+
+static const int headerSize = 16;
+
+static unsigned int typeMap[5] = {
+    GL_ETC1_RGB8_OES,
+    GL_COMPRESSED_RGB8_ETC2,
+    0, // unused
+    GL_COMPRESSED_RGBA8_ETC2_EAC,
+    GL_COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2
+};
+
+EtcTexture::EtcTexture()
+    : m_texture_id(0), m_uploaded(false)
+{
+    initializeOpenGLFunctions();
+}
+
+EtcTexture::~EtcTexture()
+{
+    if (m_texture_id)
+        glDeleteTextures(1, &m_texture_id);
+}
+
+int EtcTexture::textureId() const
+{
+    if (m_texture_id == 0) {
+        EtcTexture *texture = const_cast<EtcTexture*>(this);
+        texture->glGenTextures(1, &texture->m_texture_id);
+    }
+    return m_texture_id;
+}
+
+bool EtcTexture::hasAlphaChannel() const
+{
+    return m_type == GL_COMPRESSED_RGBA8_ETC2_EAC ||
+           m_type == GL_COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2;
+}
+
+
+void EtcTexture::bind()
+{
+    if (m_uploaded && m_texture_id) {
+        glBindTexture(GL_TEXTURE_2D, m_texture_id);
+        return;
+    }
+
+    if (m_texture_id == 0)
+        glGenTextures(1, &m_texture_id);
+    glBindTexture(GL_TEXTURE_2D, m_texture_id);
+
+#ifdef ETC_DEBUG
+    qDebug() << "glCompressedTexImage2D, width: " << m_size.width() << "height" << m_size.height() <<
+                "paddedWidth: " << m_paddedSize.width() << "paddedHeight: " << m_paddedSize.height();
+#endif
+
+#ifndef QT_NO_DEBUG
+    while (glGetError() != GL_NO_ERROR) { }
+#endif
+
+    QOpenGLContext *ctx = QOpenGLContext::currentContext();
+    Q_ASSERT(ctx != 0);
+    ctx->functions()->glCompressedTexImage2D(GL_TEXTURE_2D, 0, m_type,
+                                             m_size.width(), m_size.height(), 0,
+                                             (m_paddedSize.width() * m_paddedSize.height()) / 2,
+                                             m_data.data() + headerSize);
+
+#ifndef QT_NO_DEBUG
+    // Gracefully fail in case of an error...
+    GLuint error = glGetError();
+    if (error != GL_NO_ERROR) {
+        qDebug () << "glCompressedTexImage2D for compressed texture failed, error: " << error;
+        glBindTexture(GL_TEXTURE_2D, 0);
+        glDeleteTextures(1, &m_texture_id);
+        m_texture_id = 0;
+        return;
+    }
+#endif
+
+    m_uploaded = true;
+    updateBindOptions(true);
+}
+
+class QEtcTextureFactory : public QQuickTextureFactory
+{
+public:
+    QByteArray m_data;
+    QSize m_size;
+    QSize m_paddedSize;
+    unsigned int m_type;
+
+    QSize textureSize() const { return m_size; }
+    int textureByteCount() const { return m_data.size(); }
+
+    QSGTexture *createTexture(QQuickWindow *) const {
+        EtcTexture *texture = new EtcTexture;
+        texture->m_data = m_data;
+        texture->m_size = m_size;
+        texture->m_paddedSize = m_paddedSize;
+        texture->m_type = m_type;
+        return texture;
+    }
+};
+
+QQuickTextureFactory *QSGPkmHandler::read(QIODevice *device)
+{
+    QScopedPointer<QEtcTextureFactory> ret(new QEtcTextureFactory);
+    ret->m_data = device->readAll();
+    if (ret->m_data.isEmpty() || ret->m_data.size() < headerSize)
+        return nullptr;
+
+    const char *rawData = ret->m_data.constData();
+
+    // magic number
+    if (qstrncmp(rawData, "PKM ", 4) != 0)
+        return nullptr;
+
+    // currently ignore version (rawData + 4)
+
+    // texture type
+    quint16 type = qFromBigEndian<quint16>(rawData + 6);
+    static int typeCount = sizeof(typeMap)/sizeof(typeMap[0]);
+    if (type >= typeCount)
+        return nullptr;
+    ret->m_type = typeMap[type];
+
+    // texture size
+    ret->m_paddedSize.setWidth(qFromBigEndian<quint16>(rawData + 8));
+    ret->m_paddedSize.setHeight(qFromBigEndian<quint16>(rawData + 10));
+    if ((ret->m_paddedSize.width() * ret->m_paddedSize.height()) / 2 > ret->m_data.size() - headerSize)
+        return nullptr;
+    ret->m_size.setWidth(qFromBigEndian<quint16>(rawData + 12));
+    ret->m_size.setHeight(qFromBigEndian<quint16>(rawData + 14));
+    if (ret->m_size.isEmpty())
+        return nullptr;
+
+#ifdef ETC_DEBUG
+    qDebug() << "requestTexture returning: " << ret->m_data.length() << "bytes; width: " << ret->m_size.width() << ", height: " << ret->m_size.height();
+#endif
+
+    return ret.take();
+}
+
+QT_END_NAMESPACE
diff --git a/src/quick/scenegraph/compressedtexture/qsgpkmhandler_p.h b/src/quick/scenegraph/compressedtexture/qsgpkmhandler_p.h
new file mode 100644
index 0000000000..77097cb80a
--- /dev/null
+++ b/src/quick/scenegraph/compressedtexture/qsgpkmhandler_p.h
@@ -0,0 +1,94 @@
+/****************************************************************************
+**
+** Copyright (C) 2017 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtQuick module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QSGPKMHANDLER_H
+#define QSGPKMHANDLER_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include <QOpenGLFunctions>
+#include <QQuickImageProvider>
+#include <QtQuick/QSGTexture>
+#include <QUrl>
+
+QT_BEGIN_NAMESPACE
+
+class QSGPkmHandler
+{
+public:
+    QSGPkmHandler() {}
+
+    QQuickTextureFactory *read(QIODevice *device);
+};
+
+class EtcTexture : public QSGTexture, protected QOpenGLFunctions
+{
+    Q_OBJECT
+public:
+    EtcTexture();
+    ~EtcTexture();
+
+    void bind();
+
+    QSize textureSize() const { return m_size; }
+    int textureId() const;
+
+    bool hasAlphaChannel() const;
+    bool hasMipmaps() const { return false; }
+
+    QByteArray m_data;
+    QSize m_size;
+    QSize m_paddedSize;
+    GLuint m_texture_id;
+    GLenum m_type;
+    bool m_uploaded;
+};
+
+QT_END_NAMESPACE
+
+#endif // QSGPKMHANDLER_H
diff --git a/src/quick/scenegraph/scenegraph.pri b/src/quick/scenegraph/scenegraph.pri
index c6db3df158..b5c72f521c 100644
--- a/src/quick/scenegraph/scenegraph.pri
+++ b/src/quick/scenegraph/scenegraph.pri
@@ -220,3 +220,18 @@ qtConfig(opengl(es1|es2)?) {
         $$PWD/shaders/visualization.frag \
         $$PWD/shaders/visualization.vert
 }
+
+# Compressed Texture API
+HEADERS += \
+    $$PWD/util/qsgtexturereader_p.h
+
+SOURCES += \
+    $$PWD/util/qsgtexturereader.cpp
+
+qtConfig(opengl(es1|es2)?) {
+    HEADERS += \
+        $$PWD/compressedtexture/qsgpkmhandler_p.h
+
+    SOURCES += \
+        $$PWD/compressedtexture/qsgpkmhandler.cpp
+}
diff --git a/src/quick/scenegraph/util/qsgtexturereader.cpp b/src/quick/scenegraph/util/qsgtexturereader.cpp
new file mode 100644
index 0000000000..61729ada18
--- /dev/null
+++ b/src/quick/scenegraph/util/qsgtexturereader.cpp
@@ -0,0 +1,82 @@
+/****************************************************************************
+**
+** Copyright (C) 2017 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtQuick module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qsgtexturereader_p.h"
+
+#include <private/qtquickglobal_p.h>
+
+#if QT_CONFIG(opengl)
+#include <private/qsgpkmhandler_p.h>
+#endif
+
+QT_BEGIN_NAMESPACE
+
+QSGTextureReader::QSGTextureReader()
+{
+
+}
+
+QQuickTextureFactory *QSGTextureReader::read(QIODevice *device, const QByteArray &format)
+{
+#if QT_CONFIG(opengl)
+    if (format == QByteArrayLiteral("pkm")) {
+        QSGPkmHandler handler;
+        return handler.read(device);
+    }
+#else
+    Q_UNUSED(device)
+    Q_UNUSED(format)
+#endif
+    return nullptr;
+}
+
+bool QSGTextureReader::isTexture(QIODevice *device, const QByteArray &format)
+{
+#if QT_CONFIG(opengl)
+    if (format == QByteArrayLiteral("pkm")) {
+        return device->peek(4) == QByteArrayLiteral("PKM ");
+    }
+#else
+    Q_UNUSED(device)
+    Q_UNUSED(format)
+#endif
+    return false;
+}
+
+QT_END_NAMESPACE
diff --git a/src/quick/scenegraph/util/qsgtexturereader_p.h b/src/quick/scenegraph/util/qsgtexturereader_p.h
new file mode 100644
index 0000000000..7d2fc314a6
--- /dev/null
+++ b/src/quick/scenegraph/util/qsgtexturereader_p.h
@@ -0,0 +1,72 @@
+/****************************************************************************
+**
+** Copyright (C) 2017 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtQuick module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QSGTEXTUREREADER_H
+#define QSGTEXTUREREADER_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include <QString>
+
+QT_BEGIN_NAMESPACE
+
+class QIODevice;
+class QQuickTextureFactory;
+
+class QSGTextureReader
+{
+public:
+    QSGTextureReader();
+
+    static QQuickTextureFactory *read(QIODevice *device, const QByteArray &format);
+    static bool isTexture(QIODevice *device, const QByteArray &format);
+};
+
+QT_END_NAMESPACE
+
+#endif // QSGTEXTUREREADER_H
diff --git a/src/quick/util/qquickpixmapcache.cpp b/src/quick/util/qquickpixmapcache.cpp
index e026608150..e218b84fff 100644
--- a/src/quick/util/qquickpixmapcache.cpp
+++ b/src/quick/util/qquickpixmapcache.cpp
@@ -49,6 +49,7 @@
 #include <qpa/qplatformintegration.h>
 
 #include <QtQuick/private/qsgtexture_p.h>
+#include <QtQuick/private/qsgtexturereader_p.h>
 
 #include <QQuickWindow>
 #include <QCoreApplication>
@@ -771,8 +772,26 @@ void QQuickPixmapReader::processJob(QQuickPixmapReply *runningJob, const QUrl &u
             QFile f(localFile);
             QSize readSize;
             if (f.open(QIODevice::ReadOnly)) {
-                if (!readImage(url, &f, &image, &errorStr, &readSize, runningJob->requestSize, runningJob->providerOptions))
-                    errorCode = QQuickPixmapReply::Loading;
+
+                // for now, purely use suffix information to determine whether we are working with a compressed texture
+                QByteArray suffix = QFileInfo(f).suffix().toLower().toLatin1();
+                if (QSGTextureReader::isTexture(&f, suffix)) {
+                    QQuickTextureFactory *factory = QSGTextureReader::read(&f, suffix);
+                    if (factory) {
+                        readSize = factory->textureSize();
+                    } else {
+                        errorStr = QQuickPixmap::tr("Error decoding: %1").arg(url.toString());
+                        errorCode = QQuickPixmapReply::Decoding;
+                    }
+                    mutex.lock();
+                    if (!cancelled.contains(runningJob))
+                        runningJob->postReply(errorCode, errorStr, readSize, factory);
+                    mutex.unlock();
+                    return;
+                } else {
+                    if (!readImage(url, &f, &image, &errorStr, &readSize, runningJob->requestSize, runningJob->providerOptions))
+                        errorCode = QQuickPixmapReply::Loading;
+                }
             } else {
                 errorStr = QQuickPixmap::tr("Cannot open: %1").arg(url.toString());
                 errorCode = QQuickPixmapReply::Loading;
@@ -1233,11 +1252,23 @@ static QQuickPixmapData* createPixmapDataSync(QQuickPixmap *declarativePixmap, Q
     QString errorString;
 
     if (f.open(QIODevice::ReadOnly)) {
-        QImage image;
-        QQuickImageProviderOptions::AutoTransform appliedTransform = providerOptions.autoTransform();
-        if (readImage(url, &f, &image, &errorString, &readSize, requestSize, providerOptions, &appliedTransform)) {
-            *ok = true;
-            return new QQuickPixmapData(declarativePixmap, url, QQuickTextureFactory::textureFactoryForImage(image), readSize, requestSize, providerOptions, appliedTransform);
+        // for now, purely use suffix information to determine whether we are working with a compressed texture
+        QByteArray suffix = QFileInfo(f).suffix().toLower().toLatin1();
+        if (QSGTextureReader::isTexture(&f, suffix)) {
+            QQuickTextureFactory *factory = QSGTextureReader::read(&f, suffix);
+            if (factory) {
+                *ok = true;
+                return new QQuickPixmapData(declarativePixmap, factory);
+            } else {
+                errorString = QQuickPixmap::tr("Error decoding: %1").arg(url.toString());
+            }
+        } else {
+            QImage image;
+            QQuickImageProviderOptions::AutoTransform appliedTransform = providerOptions.autoTransform();
+            if (readImage(url, &f, &image, &errorString, &readSize, requestSize, providerOptions, &appliedTransform)) {
+                *ok = true;
+                return new QQuickPixmapData(declarativePixmap, url, QQuickTextureFactory::textureFactoryForImage(image), readSize, requestSize, providerOptions, appliedTransform);
+            }
         }
     } else {
         errorString = QQuickPixmap::tr("Cannot open: %1").arg(url.toString());
diff --git a/tests/auto/qmltest/image/logo.pkm b/tests/auto/qmltest/image/logo.pkm
new file mode 100644
index 0000000000..c0987c5c36
--- /dev/null
+++ b/tests/auto/qmltest/image/logo.pkm
diff --git a/tests/auto/qmltest/image/tst_image.qml b/tests/auto/qmltest/image/tst_image.qml
index 6f2164363c..69ef4d1868 100644
--- a/tests/auto/qmltest/image/tst_image.qml
+++ b/tests/auto/qmltest/image/tst_image.qml
@@ -112,6 +112,11 @@ Item {
         fillMode: Image.TileHorizontally
     }
 
+    Image {
+        id: pkmImage
+        source: "logo.pkm"
+    }
+
     TestCase {
         name: "Image"
 
@@ -212,5 +217,9 @@ Item {
             compare(tileModes3.fillMode, Image.TileHorizontally)
         }
 
+        function test_pkmImage() {
+            compare(pkmImage.width, 256)
+            compare(pkmImage.height, 256)
+        }
     }
 }